Abrading wheel

ABSTRACT

An abrading device particularly adapted for grinding rubber, plastic and various other nonmetallic materials, comprising a single-piece, relatively thin disk member having a flat planar hub portion and a serpentine-like undulating peripheral portion displaced out of the plane of the flat disk and formed to provide a series of radially extending vane-like disk portions between the edge and hub portions of said member which serve as pumping vanes to circulate cooling air or other fluid about all surfaces of the disk and across the outer edge thereof to dissipate heat and to prevent the buildup of ground particles on the disk surfaces. An abrasive in the form of a carbide grit or other suitable abrasive material is bonded to the peripheral face of the wheel.

United States Patent [1 1 Oliver 1 [451 July 3,1973

[ ABRADING WHEEL Lloyd R. Oliver, Algonac, Mich. [73] Assignee: L. R. Oliver, Inc., Algonac, Mich. 22 Filed: Jan. 14, 1972 [2]] App]. No.: 217,790

Related US. Application Data [63] Continuation-impart of Ser. No. 54,888, July 15,

1970, abandoned.

[75] lnventor:

2,8ll,960 ll/l957 Fessel l25/l5 Primary Examiner-Donald 0. Kelly Attorney-Johnson, Dienner, Emrich. Verbeck 8L Wagner [57] I ABSTRACT An abrading device particularly adapted for grinding rubber, plastic and various other nonmetallic materials, comprising a single-piece, relatively thin disk member having a flat planar hub portion and a serpentine-like undulating peripheral portion displaced out of the plane of the flat disk and formed to provide a series of radially extending vane-like disk portions between the edge and hub portions of said member which serve as pumping vanes to circulate cooling air or other fluid about all surfaces of the disk and across the outer edge thereof to dissipate heat and to prevent the buildup of ground particles on the disk surfaces. An abrasive in the form of a carbide grit or other suitable abrasive material is bonded to the peripheral face of the wheel.

28 Claims, 16 Drawing Figures PATENTEDJULB I315 3.742.655 smears ABRADING WHEEL This is a continuation-in-part of my application for patent Ser. No. 54,888 filed July 15, 1970, now abandoned, and comprises an invention in the field of cutting and abrading or grinding devices.

More particularly, it relates to a rotating abrading wheel having an abrasive material such as carbide grit bonded to its outer peripheral surface or face and incorporating means for ventilation and cooling of the wheel which prevent the buildup of heat due to friction and also keep the wheel relatively clean of particles ground off the workpiece.

BACKGROUND OF THE INVENTION Up until the present time various cutting and abrading wheels have been utilized to grind nonmetallic ma terials incorporating a steel base member having a peripheral surface to which is bonded a cutting material such as carbide grit or the like. The width of the peripherally extending abrading surface of such wheels has been made equal to the width of the surface to be abraded, and hence such wheels may be referred to as full face wheels. The base member of such devices may be machined, spun-formed, heat-drawn or of welded multipiece construction, and generally incorporates some type of blade or fan to provide air circulation within and around the device to dissipate heat. Holes or slots are then provided in or near the peripheral wheel surface to circulate the air about the surfaces of the device in actual contact with the workpiece. Such prior art devices have not proved entirely satisfactory because the hot cuttings of rubber or plastic material being cut impinge upon and stick to the fan blades or vanes and upon the inside of the peripheral cutting band, and eventually effectively block air circulation through the wheel, causing it to become overheated due to friction.

Because these full face wheels have an appreciable surface area constantly in contact with the workpiece being'ground, they develop excessive friction which produces a great amount of heat, and it is difficult if not impossible to dissipate the heat. As the width of the abrasive wheel surface increases, the heat due to friction is correspondingly increased, and thus with wider wheels, the problem of heat buildup is magnified.

An exemplification of the full face abrading wheels above referred to is U.S. Pat. No. 3,145,511, of which I am the co-inventor. Such shows a so-called full face wheel having a peripheral band-like rim connected to a base member comprising a pair of spaced flat disks having air inlet apertures spaced about the disks and vanes extending axially inwardly from each disk to provide an air pump within the wheel. Air outlet apertures are provided adjacent the peripheral rim, whereby cooling air is drawn through the holes in the disk and exhausted through the apertures adjacent the rim to keep the abrading portion of the device cool. Due to the fact that an appreciable surface area of the wheel is constantly in contact with the workpiece being ground, a great quantity of heat due to friction is generated within the wheel, and it is virtually impossible to dissipate the heat even with a most efficient fan design built into the wheel base member. As the abrading wheel heats up during use, the particles of ground material flying off the workpiece tend to stick to the wheel surfaces, plugging up the air apertures within the wheel, and rendering the fans or vanes substantially useless.

One of the features of the abrading wheel disclosed herein is the fact that less abrading surface of the peripheral wheel area bears against the workpiece at any given instant, thereby materially reducing the frictional force as compared to the prior art full face widths, and thus generating much less heat within the device itself. On the other hand, the effective width of the abrading wheel can be maintained similarly to the full face wheels, so that a predetermined surface area may be ground in the workpiece. Thus, while the instant device obviates the undesirable results obtained with prior art full face wheels by materially reducing the surface area in contact with the workpiece to prevent heat buildup due to friction, it at the same time retains the desirable characteristic of the prior art in being able to abrade a workpiece surface of virtually any desired width.

Other desirable characteristics of the instant device are an ability to penetrate the workpiece surface to a greater extent than was possible with the prior art wheels, and hence more efficiently shear, rip and tear through the rubber or other material. Inaddition, there are no pockets or areas of the wheel upon which the workpiece particles may build up or be trapped, and the structure of the wheel provides for most efficient air circulation about all of the wheel surfaces to abstract built up heat in the wheel member itself and to rid the wheel surfaces of workpiece particles more effectively.

SUMMARY An abrading device adapted to be mounted on a shaft for rotation comprising a rigid circular disk having a substantially flat planar hub portion provided with a central opening to accommodate said shaft, a continuous undulating peripheral edge portion of predetermined axial dimension, and an intermediate annular portion connecting the hub and peripheral edge portions which defines a series of spaced apart, integral vane-like members extending generally radially of the disk on opposite sides thereof and of increasing axial dimension from the hub to the peripheral edge for circulating cooling fluid about the entire disk during its rotation, and an abrasive material bonded to the face of said peripheral edge of the disk.

Among the advantages of the abrading wheel embodying the instant invention are that at any given moment only a small area of the wheel surface is in contact with the workpiece, allowing greater penetration of the abrading surface and resulting in more efficient cutting and shearing of the workpiece material.

A further feature is the creation during wheel rotation of high air or other coolant circulation rate about all of the wheel surfaces to abstract heat generated therein due to friction and to dissipate the hot workpiece particles efficiently and effectively.

A still further feature is that the wheel contains no pockets, crevices or interstices where the particles of cost and simplicity of manufacture as compared with prior art devices which were cast, spun-formed or machined and incorporated a plurality of separate parts which had to be assembled to provide the ultimate product.

The wheel of this invention is considerably less costly to manufacture, and is appreciably lighter in weight than prior art full face wheels. In addition it requires much less abrasive material for the same width of cut. The carbide grit material and brazed bonding metals used to secure the grit to the wheel are quite costly, and therefore a reduction in the amount of materials used results in a substantial cost saving. For example, a socalled full face wheel having a width of 0.75 inches requires that the carbide grit be applied across the entire 0.75 inch width. The wheel of the instant invention made out of 0.125 inch sheet metal disk requires only one-sixth the amount of carbide grit. The limited area of contact of the instant wheel permits a greater penetration of the abrasive material into the workpiece under any given total pressure than can be achieved by the so-called full face wheels. This enables a deeper cut into the workpiece for any given abrasive grit size, and also requires less power to drive the wheel in order to remove a predetermined amount of stock from the workpiece than that required for the full face wheels.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an abrading wheel embodying the invention;

FIG. 2 is a front elevation of the wheel shown in FIG. 1 on a slightly enlarged scale;

FIG. 3 is a side elevation of the wheel shown in FIG.

FIG. 4 is a side elevation similar to FIG. 3 showing a modified form of a device embodying the invention;

FIGS. 5 through 9 comprise partial sectional views taken through the marginal edge portion of the devices shown in FIGS. 1-3 and illustrate various peripheral face configurations which abrading wheels of this invention may comprise in accordance with the use to which they are put;

FIG. 10 is a front elevational view of a further modification of the invention;

FIG. 11 is a sectional view taken through the device of FIG. 10 along lines 11-11 and looking in the direction indicated by the arrows;

FIGS. l2, l3 and 14 comprise partial sectional views taken through the marginal edge portion of the device shown in FIGS. 10 and 11 and illustrate means for effectively increasing the depth of penetration of the abrading edge of the device; the means being also adaptable to the devices illustrated by FIGS. 1-9;

FIG. 15 is a circumferential view showing a plurality of the grinding wheels mounted together in intermeshed relation upon a shaft; and

FIG. 16 is a circumferential view similar to FIG. 11 showing a plurality of the wheels embodying the invention mounted in stacked relation upon a shaft.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

There is shown in FIGS. 1-3 inclusive a grinding or abrading wheel embodying the instant invention indicated generally by the numeral 20, which wheel is formed from a flat disk of rigid metal sheet stock into the configuration shown by a stamping die or the like, The wheel once formed exhibits a central circular aperture 22 extending therethrough so as to receive a drive shaft (not shown) on which the device is adapted to be mounted for rotation about its axis A (FIG. 2). Surrounding aperture 22 is a generally flat planar hub portion 24, the opposed sides 24a and 24b of which are machine ground to a parallel relation and at right angles to said axis A upon which the wheel rotates in use. The outer peripheral edge 26 of the disk has a face 28 (FIG. 3) armed with a material 28a such as carbide grit of a particle size less than the disc edge width which provides an abrading surface about the wheel periphery. Between said outer edge 26 of the wheel and its central hub portion 24 the intermediate portion 36 of the wheel is displaced by the stamping die(s) so that it defines a plurality of radially extending vane-like portions 30 having circumferentially spaced crests 32 which are alternately disposed on opposite sides of the flat hub portion 24 and also inclined to the flat planar sides 24a and 24b thereof. The crest 32 of each said vane portions 30 are connected to the crests of the next succeeding and preceding vanes by divergingly related transverse portions or vane sides 34 such that said outer edge 26 and including its face 28 and portion 36 between said edge and hub portion 24 comprise a continuous undulating configuration.

In the embodiment illustrated by FIGS. 1-3 crests 32 have opposed flat surfaces and their bounds 38 being essentially radial are wider at the outer edge 26 of the wheel than at their inner ends adjacent the hub portion 24 where they effectively merge into the planar disposition of the surrounding surface. However, in the embodiment illustrated by FIGS. 10 and 11, crests 32 are more narrow at the outer edge 26 of the wheel than at their inner end and said bounds 38 are not radial. In our experience to date, a most satisfactory pumping of air or other cooling fluid outwardly through the outer edge 26 of the wheel is obtained when the crests 32 are inclined at about 30 to the plane of the sides 24a 24b of the hub portion 24, the bounds 38 of said crests are at an included angle in the order of 20 (10 offset from a bisecting radius) and the angle at which the transverse vane sides 34 are to said sides 24a and 24b of the hub portion does not exceed 30". Bounds 38 of the crests 34 may intersect substantially at the outer edge 26 of the wheel or slightly outside thereof. Preferably,

crest sector 32a at edge 26 does not exceed 7 or 8.

During the stamping operation which forms member 20 into the shape shown in FIGS. 1-3 or 10-11, some thinning or distortion of the metal inevitably occurs and therefore after the metal is formed to the desired shape its outer peripheral edge 26 is ground or machined into a true circular configuration in elevation as shown in FIG. 2. This operation is, of course, performed prior to the deposition of the abrading material 28a on the outer peripheral face 28 of said edge. The aforedescribed machine grinding of the opposed sides 24a and 24b of the hub portion also takes place after the stamping operation, but before application of grit to face 28 of the disk edge 26. The extent and also the inclination of the crests 32 are a function of the diameter of the abrading wheel 20 and the required abrading swath a of the wheel (FIGS. 3 and 11). The disk 20 is preferably of substantially uniform thickness throughout, except that the outer peripheral edge 26 thereof may be thinned as afterwards described and the exact thickness for any given diameter of wheel will depend upon the amount of deformation required of the disk to set the crests 32 at an angle which will produce the desired swath width a and the vane sides 34 at their appropriate shear angle. The minimum thickness of disk is also a function of the disk diameter, and smaller diameters may be formed of thinner materials, while large diameter disks must necessarily be made of thicker metal to insure against tearing of the metal during deformation and provide sufficient rigidity in the finished product.

It has been found that a disk having an outer diameter of approximately 8 inches may be formed of material of ;8 inch thickness, and the effective abrading swath width a of the resultant abrading device may be for example three-fourths of an inch. As can be seen from an examination of FIG. 3, the effective abrading width of the wheel will be equal to the distance between crests of adjacent undulations on opposite sides of the wheel, i.e. the distance a which is measured axially between crests portion 32 on opposite sides of the wheel as shown in FIGS. 3 and 11. As the distance between such surfaces defines the effective abrading width of the wheel, after the originally flat disk is deformed into the desired shape, it may be desirable to grind the lateral marginal edges defined by the surfaces as shown at 40 in FIG. 2 to provide a uniform effective width throughout the wheel circumference.

Shown in FIG. 4 is a slightly modified form of grinding or abrading device in which the undulating outer peripheral edge is formed by displacing the material in one direction only from the original flat disk, rather than to opposite sides as shown and described previously in connection with the embodiments of FIGS. 1-3 and -1 1. Such disk is provided with a bore 22 in similar fashion as previously described, and also with a hub portion 24 encircling the bore. The radially outwardly extending vane-like portions 46 of its intermediate section 42, however, are displaced in one direction only out of the original plane of the disk toward the right as shown in FIG. 4, thereby providing the undulating outer peripheral edge 48 having the abrasive grit bonded to face 50 thereof as shown.

Comparing FIG. 3 to FIG. 4, it can be seen that the undulating intermediate portion and peripheral edge of the device may be formed in a variety of shapes, depending upon the particular application to which the device is to be fit. In FIG. 3 there is shown a device having undulations, the crests 32 of which are essentially flat and with diverging vane sides 34. Vane sides 34 interconnect the crests 32 of adjacent undulation, extending angularly therebetween across the plane of the hub sides at a straight angle. On the other hand, the undulations or vanes 46 on the device depicted in FIG. 4 define a substantially continuously curved path which may be of generally sinusoidal shape having arcuate crests 52 and diverging sides 54, every other crest lying between planes including the sides of the hub portion and the alternate crests lying to one side thereof. The number of undulations, it'will be appreciated, is determined by the diameter of the disk, the thickness thereof and the effective abrading swath required of the wheel, keeping in mind the importance of avoiding substantial distortion of, the metal when inclining the vane crests and also that the shear angle of the vane sides should not exceed 30 for effective shearing.

FIGS. 5 through 9 illustrate representative edge configurations which can be provided on the devices shown in either FIGS. 1-3, FIG. 4 or FIGS. 10-11 to provide a desired configuration of workpiece upon which the device is used. Thus the peripheral edge of i the wheel may be ground or machined in a direction parallel to the disk axis, that is' the effective width of the wheel, into any desired configuration to provide a resultant configuration of workpiece corresponding to such peripheral edge configuration. In FIG. 5 there is shown a peripheral edge formed into a convex or toric form 60 to provide a correspondingly concave configuration of the workpiece when the wheel is used to abrade the same. In FIG. 7, there is shown a concave peripheral configuration 62, which will provide a convex workpiece configuration and FIG. 6 shows a flat axially extending or cylindrical peripheral surface 64 which, of course, will provide a correspondingly flat surface on the workpiece being abraded by the device. FIG. 8 shows the flat axially extending peripheral surface 64 of the FIG. 6 embodiment provided with a notch 66. The device is therefore particularly useful for abrading two narrow bands. FIG. 9 illustrates at 68 a surface that is ground flat but enclosed at an angle rendering the device particularly useful in feathering the area on a newly buffed recappable tire casing where the newly applied material merges with the side wall. Various other configurations may be provided, as desired, to accomplish any workpiece surface configuration.

FIG. 15 and FIG. 16 show devices comprising a plurality of single abrading disks which may be mounted on a common shaft to produce an effective abrading width greater than that achievable by a single disk. The disks 20 shown in FIGS. 15 and 16 are of the general form previously described with reference to FIGS. 1-3 and FIGS. 10-11. Referring particularly to FIG. 15, it can be seen that the plurality of abrading disks 20 are disposed in uniformly spaced apart relation with the peripheral edges thereof being uniformly spaced apart throughout their length. The wheels are therefore intermeshed, and provide when so arranged a continuous abrading width equal to the distance defined by the dimension labeled xx in FIG. 15. When assembling the members 20 on a common shaft in the arrangement shown in FIG. 15, spacers are provided in the form of washers or the like (not shown) each having a central aperture and disposed on the shaft intermediate each adjacent pair of disks 20. In addition, and particularly if the disks employed are of fairly large diameter, additional spacers such as shown in FIG. 15 at 70 may be brazed or otherwise secured to the disk surfaces spaced radially inwardly from the peripheral edge thereof to maintain the disks in uniformly spaced apart relation throughout their surface area.

FIG. 16 shows a plurality of the devices 20 for mounting on a common shaft arranged in slightly different fashion than depicted in FIG. 15. In FIG. 16 the oppositely disposed crests 32 on adjacent disks 20 are disposed in surface abutting relation, and may be secured together as by brazing, riveting, or the like to provide a stacked series of disks rather than the intermeshed configuration shown in FIG. 15. The arrangement shown in FIG. 16 provides an effective abrading width for the workpiece equal to the dimension indicated by y-y in FIG. 16.

When the abrading devices are intermeshed as shown in FIG. 15 or stacked as shown in FIG. 16 to provide a device having a greater effective abrading width, air inlet apertures are provided in the disks, such apertures being formed perferably in the hub portion 24 of each disk, to permit entry of air or other cooling fluid such as water or steam to enter between the disks and be pumped by the vane-like disk portions to dissipate the heat of friction resulting from the abrading action of the device against the workpiece, and also to keep the disk surfaces free from particles of abraded material.

Referring to FIG. 4, it will be apparent that the device shown therein could be combined with other similar devices to provide a wider effective abrading width device by positioning the devices on a common shaft, with pairs of devices disposed in allochiral relation on the shaft, that is with the hub portions 24 of adjacent disks in surfaceabutting relation, and with each undulating edge of such disks being interleaved with the corresponding undulating edge of another disk.

It will be obvious to those skilled in the art that by utilizing a device for abrading of the character disclosed herein, the surface contact between the device and the workpiece being abraded will be appreciably less than with the prior art so called full face wheels. For example, the surface area contact utilizing a wheel embodying the instant invention having a given diameter and a thickness of one-eighth inch will be one-eighth inch times the circumferentially measured length in contact with the workpiece at any given instant, irrespective of the effective width of the wheel, which is the axial distance between the surfaces 32 and 34 shown in FIG. 3.

Utilizing a prior art full face width wheel, the area of contact between the wheel surface and the workpiece at any given instant will be the full width of the wheel multiplied by the circumferential dimension in contact with the workpiece, which is dependent upon wheel diameter. Thus, assuming a disk width of one-eighth inch and an effective abrading width of five-eighths inches, the area of contact of the device embodying the instant invention would be approximately one-fifth the area of contact utilizing a full face wheel, and thus the frictional force and the heat created by such friction will be approximately 20% of that created as compared to a full face wheel.

As earlier alluded to, wheels 20 of this invention are particularly useful in the manufacture of white wall tires as for example to grind away the black outer material which covers a white circular band embedded in the sidewall of a tire carcass so as to expose a sharp uniform circular stripe or concentric stripes characteristic of so-called whitewall tires. The peripheral configuration of grinding wheels as illustrated by FIGS. through 8 are particularly useful for this purpose, the configuration of FIG. 8 being useful to produce concentric stripes. The wheels of this invention are also particularly useful to grind away the excess rubber at the junction of the rubber tread newly applied to a tire carcass as a part of the retreading operation to smooth or feather" the union. The conical" configuration illustrated by FIG. 9 is particularly useful for this purpose. Many other uses of the abrading wheels of this invention are possible both inside and outside the tire manufacturing and retreading industries.

The action of abrading wheels of this invention is the combined effect of the diameter and edge thickness of the wheel, the angle at which the vanes side 34 are disposed and the cutting points of the abrasive grit 28a with which said edge of the wheel is coated. Edge 26 of the wheels penetrate the material of the tire carcass with rotation of the wheel to locate the action of the abrasive grit points deep into the material; and the angle at which the leading edge of the vane sides 34 is so disposed that it shears the material ruptured by the deeply penetrating edge 26 so as to remove relatively large cuttings or pieces with a generation ofa minimum amount of smoke and fine dust. For maximum penetration, disk edge 26 should be as thin as possible consistent with the rigidity requirements of the steel or other material of which the wheel disk is comprised. FIGS. 12, 13 and 14 illustrate how the wheel edge can be effectively thinned to further increase the penetration depth of the wheel without sacrificing rigidity of the wheel construction. Thus, FIG. 12 illustrates that the cross section width of edge 26 can be reduced by beveling one corner thereof as at 72. Both corners thereof can be beveled as illustrated at 72 and 74 in FIG. 13 or said edge can be grooved circumferentially as indicated at 76 in FIG. 14. Instead of beveling edge 26, said edge could be provided with a radius. Thus by any of the means illustrated by FIGS. 12, 13 and 14 the edge width of the disc cap be reduced to at least one-third its full width, or even smaller. In FIG. 14, groove 76 divides said edge into two spaced cutting edges, each one-third the full edge width of the wheel. Advantageously, groove 76 is cut to a depth in the order of three times the width of the disk. The edge thickness of the disk, however, may be reduced to any thickness up to the grit particle size which may be as low as 0.005 inches. It will be appreciated that the abrasive grit should be of a size less than the disk edge width and preferably less than one-third said disk edge width in order to provide face 28 of the disk edge 26 with as many cutting points as possible. The angle at which the leading edge of the vane sides 34 is disposed is also important to provide a maximum shear effect with a minimum application of pressure.

It will be recognized that as the angle of the leading edge of the vanes approaches parallelism with the direction of rotation of the wheel, there is less interruption of the wheel contact with the work piece and the action of the wheel takes on more the characteristics of a full face wheel. On the other hand, as the angle of the leading edge of the vanes becomes larger and larger, that is approaches parallelism with the axis of rotation, the effective contact width of the edge also increases. In our experience to date it has been found that a satisfactory compromise obtains where the vane sides are so set that the leading edges of the vane sides are at an angle between 5 and 30 with respect to said direction of rotation, that is to the plane of the sides 24a, 24b of the wheel hub. Possibly the best results are obtained when said angle is between 5 and 15. Where the shear angle much exceeds 30 there is also an increased amount of vibration because of the relatively wider spacing of the vanes and the resultant intermittent contact of the wheel with the work piece. On the other hand, as said shear angle decreases below 30 the pressure required to effect the cutting action also decreases so that there is less scorching of the rubber tire carcass.

The swath cut by the wheel corresponds to the axial spacing of the crests as indicated at a in FIGS. 3 and 4. This in turn is dependent on the thickness of the metal and the number of vanes. For example, a wheel diameter of 8 inches, when formed of a particular steel, requires a metal thickness of approximately threesixteenths inch and four vanes on either side in order to be stretched to a 1 inch swath cut whereas A; inch thickness of the same metal thus stretched would tear at the bounds 38 of the vane periphery. By reducing edge thickness, penetration can be in creased as earlier mentioned. However, minimum thickness is also determined by how far the metal can be stretched to form vanes giving the required abrading swath width and by what thickness is required to retain the overall strength of the wheel.

The longer the vanes the more effective is the pumping action thereof in circulating ambient air, gaseous or other liquid coolants. For this purpose, the vanes should be extended to as close to the central hub portion as possible, considering the necessity to provide clearance about the shaft for mounting structure, etc. In experience to date it has been found that the length of the vanes considered radially of the wheel should not be less than the abrading swath a and in practice good results can be obtained where the length of vanes range between 1% and 3 times said width a. In one practical form of the invention the vane length approximated one-third the diameter of the wheel or two-thirds its radius. However, good results in collecting and circulating ambient air outwardly through the undulated edge of the wheel so as to dissipate heat and deter particle build-up during abrading action has been obtained where the vane lengths have varied from roughly 60 to 20 percent of the wheel radius.

The vanes or undulations may also be utilized for distributing gaseous or liquid coolants such as steam or water over the surface of the tire carcass against which the abrasive action of the rotating wheel edge is directed. In such arrangements the steam, water or other fluid may be directed against one or both surfaces of the wheel immediately outside the hub portion so as to be thrown outwardly with centrifical force and directed by the vane sides outwardly through the wheel edge between the undulations.

A good quality steel is the material of preference for disk 20, because of the fact that the braze metals conventionally used with tungsten carbide are of such high melting temperatures. However, it is also possible that both resin bonded and vitreous bonded refractory grain could be molded to the required wheel shapes.

Abrading wheels of this invention are particularly useful for abrading nonme'tallic material such as rubber, plastics, and the like; and for such use, it is con templated that the peripheral face 28 of the wheels will be armed with an abrasive grit comprising crushed carbide brazed to the wheel surface with copper or other braze metals. However, it will be apparent that other abrading materials may be utilized in place of the carbide grit. For example, in abrading certain materials, it appears possible that the wheel might be armed with less costly silicon carbide grit or aluminum oxide grit bonded to the wheel periphery with a vitreous or resin bonding material. As the instant device remains much cooler during the abrading operation than previous devices, certain applications with softer workpiece materials may well be of such character as to enable the use of silicon carbide or aluminum oxide grit without weakening of the grit bonds or shattering due to differentials in coefficients of expansion that elevated temperatures cause.

From the above description of preferred embodiments of the invention it will be apparent that all of the recited objects, advantages and features of the invention have been demonstrated as obtainable in a highly practical, efficient and satisfactory manner.

Thus having described my invention, I claim:

1. a rotatable abrading wheel useful to finish the'surface of rubber articles such as tire casings comprising a thin rigid metal disk having a central hub portion with parallel flat opposed surfaces and a central opening which receives a drive shaft for rotating the wheel about its axis, a circular-shaped axially undulated outer edge the peripheral face of which has a coating of abrasive grit bonded thereto, and an intermediate abrasivefree, axially-undulated annular portion therebetween, the undulated shape of said circular outer edge'and intermediate annular portion being coterminous and comprising circumferentially spaced radially extending crests and intervening transversely extending side portions, each said crests being inclined axially of the wheel with respect to the next adjacent crest and at the outer edge of the wheel being axially spaced from the next adjacent crest by a distance several times the thickness of the disk itself, the outer edge of saidtransversely extending side portions together constituting circumferentially spaced thin shear edges having an axial extent corresponding to the axial displacement of the crests and an angular disposition to the planar sides of the hub portion such that said shear edges locate the abrasive grit into the surface of an article against which the wheel is rotated to shear a swath therethrough of a width several times that of the disk, the'axial displacement of said crests and axial width of the intervening side portions progressively decreasing radially from their maximum displacement and width at the outer edge of the wheel to adjacent the central hub portion where said crests and side portions merge into the hub portion to collectively constitute long radial vanes which collect and pump ambient air from adjacent the hub portion of the wheel outwardly through the undulated outer edge of the wheel and about said shear edges to abstract heat generated therein due to friction during the shearing action of the wheel and to deter build-up therein of particles sheared by said edges.

2. An abrading wheel as claimed in claim 1 wherein the transversely extending side portions are disposed at an angle less than 30 to the flat central hub portion.

3. An abrading wheel as claimed in claim 1 wherein alternate ones of said crests lie in the plane of the flat hub portion.

4-. An abrading wheel as claimed in claim 1 wherein the crests have a circumferential width at the outer edge of the wheel which is less than at their inner ends adjacent the hub portion.

5. An abrading wheel as claimed in claim 4 wherein the bounds of said crests are disposed at approximately 10 to a radial bisector of said crests.

6. An abrading wheel as claimed in claim 1 wherein the crests have a length from about 1% to 3 times the effective abrading swath of the wheel.

7. An abrading wheel comprising a relatively thin rigid disk-like member of circular shape having an outer edge containing abrasive means on its peripheral face, a flat central hub portion containing an opening which receives a drive shaft for rotation of the wheel about its axis, and an intermediate annular portion between its outer edge and flat hub portion, said outer edge and intermediate annular portion of the disk-like member having an axially undulated shape constituted by a series of circumferentially related undulations having radially extending, axially spaced crests and transversely extending sides connecting between crests of adjacent undulations, each said crests being axially displaced at their outer edge from the next adjacent crest and at their opposite end merging into adjacent the flat sides of the hub portion, the connecting sides of said undulations being generally wedge shape and disposed at an angle less than 30 to said flat sides of the hub portion, sa'id undulated outer edge having an effective abrading swath with rotation of the wheel that is wider than the thickness of the disk-like member.

8. An abrading wheel as claimed in claim 7 wherein the angle of said connecting sides of the undulations is in the order of to 15 degrees to the flat sides of the hub portion.

9. An abrading wheel as claimed in claim 7 wherein the abrasive means comprises a coating of abrasive grit effectively bonded to the peripheral face of said edge and of a grit size less than the edge face width.

10. An abrading wheel as claimed in claim 7 wherein the crests of said undulations at the outer edge of the disk-like member are displaced uniformly in opposite directions from the flat sides of the central hub portion.

1 1. An abrading wheel as claimed in claim 7.wherein the crests of every other undulation are disposed between parallel planes comprising the flat sides of the central hub portion.

12. An abrading wheel as claimed in claim 7 wherein the crests of the undulations are generally flat and radially inclined to the plane of the hub portion.

13. An abrading wheel as claimed in claim 7 wherein the undulations define a series of continuous sinusoidal waves.

14. An abrading wheel as claimed in claim 7 wherein the crests of the undulations are effectively wider at their inner ends adjacent the hub portion than at the outer edge of the disk-like member.

15. An abrading wheel as claimed in claim 7 wherein the undulations including their crests and transverse connecting sides have a radial extent at least as long as the effective abrading width of the wheel and in the order of 60 percent of the wheel radius.

16. An abrading wheel as claimed in claim 7 wherein the peripheral edge surface of the disk-like member is narrower than the remaining thickness of said member.

17. An abrading wheel as claimed in claim 7 wherein the peripheral edge surface of the disk-like member contains at least one circumferential extending groove therein intermediate the opposed side surfaces of said edge.

18. An abrading wheel as claimed in claim 7 wherein the peripheral face of the wheel comprises the undulated outer edge of the disk-like member and is cylindrical in configuration.

19. An abrading wheel as claimed in claim 7 wherein the peripheral face of the wheel comprises the undulated outer edge of the disk-like member and is the frustrum of a cone centered on the axis of the wheel.

20. An abrading wheel as claimed in claim 7 wherein the peripheral face of the wheel comprises the undulated outer edge of the disk-like member and is toric in configuration.

21. An abrading wheel as claimed in claim 7 wherein the peripheral face of the wheel comprises the undulated outer edge of the disk-like member and is concave in section.

22. The abrading wheel claimed in claim 1 characterized in that said undulations have a radial dimension equal to or greater than 25 percent of the radius of said disk.

23. The abrading wheel claimed in claim 1 characterized in that its hub portion lies in a plane substantially equidistantly spaced axially between opposite crests of the undulations.

24. The abrading wheel as claimed in claim 1 characterized in that said hub portion lies in substantially the same plane as one of the crests of said undulations.

25. An abrading device comprising a plurality of rigid disks each as claimed in claim 1 and positioned in adja cent coaxial relation for mounting on a shaft.

26. An abrading device as claimed in claim 25 having spacer means positioned between the hub portions of adjacent disks to maintain them in predetermined spaced relation.

27. The abrading device defined in claim 25 characterized in that each of said disks is circumferentially offset from adjacent disks whereby the peripheral edge portions of adjacent disks are intermeshed and uniformly spaced apart throughout their circumferential length.

28. The abrading device defined in claim 25 characterized in that said disks are aligned with the extremities of the undulations on adjacent disks in abutment with each other. 

2. An abrading wheel as claimed in claim 1 wherein the transversely extending side portions are disposed at an angle less than 30* to the flat central hub portion.
 3. An abrading wheel as claimed in claim 1 wherein alternate ones of said crests lie in the plane of the flat hub portion.
 4. An abrading wheel as claimed in claim 1 wherein the crests have a circumferential width at the outer edge of the wheel which is less than at their inner ends adjacent the hub portion.
 5. An abrading wheel as claimed in claim 4 wherein the bounds of said crests are disposed at approximately 10* to a radial bisector of said crests.
 6. An abrading wheel as claimed in claim 1 wherein the crests have a length from about 1 1/2 to 3 times the effective abrading swath of the wheel.
 7. An abrading wheel comprising a relatively thin rigid disk-like member of circular shape having an outer edge containing abrasive means on its peripheral face, a flat central hub portion containing an opening which receives a drive shaft for rotation of the wheel about its axis, and an intermediate annular portion between its outer edge and flat hub portion, said outer edge and intermediate annular portion of the disk-like member having an axially undulated shape constituted by a series of circumferentially related undulations having radially extending, axially spaced crests and transversely extending sides connecting between crests of adjacent undulations, each said crests being axially displaced at their outer edge from the next adjacent crest and at their opposite end merging into adjacent the flat sides of the hub portion, the connecting sides of said undulations being generally wedge shape and disposed at an angle less than 30* to said flat sides of the hub portion, said undulated outer edge having an effective abrading swath with rotation of the wheel that is wider than the thickness of the disk-like member.
 8. An abrading wheel as claimed in claim 7 wherein the angle of said connecting sides of the undulations is in the order of 5 to 15 degrees to the flat sides of the hub portion.
 9. An abrading wheel as claimed in claim 7 wherein the abrasive means comprises a coating of abrasive grit effectively bonded to the peripheral face of said edge and of a grit size less than the edge face width.
 10. An abrading wheel as claimed in claim 7 wherein the crests of said undulations at the outer edge of the disk-like member are displaced uniformly in opposite directions from the flat sides of the central hub portion.
 11. An abrading wheel as claimed in claim 7 wherein the crests of every other undulation are disposed between parallel planes comprising the flat sides of the central hub portion.
 12. An abrading wheel as claimed in claim 7 wherein the crests of the undulations are generally flat and radially inclined to the plane of the hub portion.
 13. An abrading wheel as claimed in claim 7 wherein the undulations define a series of continuous sinusoidal waves.
 14. An abrading wheel as claimed in claim 7 wherein the crests of the undulations are effectively wider at their inner ends adjacent the hub portion than at the outer edge of the disk-like member.
 15. An abrading wheel as claimed in claim 7 wherein the undulations including their crests and transverse connecting sides have a radial extent at least as long as the effective abrading width of the wheel and in the order of 60 percent of the wheel radius.
 16. An abrading wheel as claimed in claim 7 wherein the peripheral edge surface of the disk-like member is narrower than the remaining thickness of said member.
 17. An abrading wheel as claimed in claim 7 wherein the peripheral edge surface of the disk-like member contains at least one circumferential extending groove therein intermediate the opposed side surfaces of said edge.
 18. An abrading wheel as claimed in claim 7 wherein the peripheral face of the wheel comprises the undulated outer edge of the disk-like member and is cylindrical in configuration.
 19. An abrading wheel as claimed in claim 7 wherein the peripheral face of the wheel comprises the undulated outer edge of the disk-like member and is the frustrum of a cone centered on the axis of the wheel.
 20. An abrading wheel as claimed in claim 7 wherein the peripheral face of the wheel comprises the undulated outer edge of the disk-like member and is toric in configuration.
 21. An abrading wheel as claimed in claim 7 wherein the peripheral face of the wheel comprises the undulated outer edge of the disk-like member and is concave in section.
 22. The abrading wheel claimed in claim 1 characterized in that said undulations have a radial dimension equal to or greater than 25 percent of the radius of said disk.
 23. The abrading wheel claimed in claiM 1 characterized in that its hub portion lies in a plane substantially equidistantly spaced axially between opposite crests of the undulations.
 24. The abrading wheel as claimed in claim 1 characterized in that said hub portion lies in substantially the same plane as one of the crests of said undulations.
 25. An abrading device comprising a plurality of rigid disks each as claimed in claim 1 and positioned in adjacent coaxial relation for mounting on a shaft.
 26. An abrading device as claimed in claim 25 having spacer means positioned between the hub portions of adjacent disks to maintain them in predetermined spaced relation.
 27. The abrading device defined in claim 25 characterized in that each of said disks is circumferentially offset from adjacent disks whereby the peripheral edge portions of adjacent disks are intermeshed and uniformly spaced apart throughout their circumferential length.
 28. The abrading device defined in claim 25 characterized in that said disks are aligned with the extremities of the undulations on adjacent disks in abutment with each other. 